Machining Vibration Prevention via Modulated Cutting Speed

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Solution Overview

Problem

Existing machining simulation tools are inadequate for predicting and preventing vibrations in large-dimensioned workpieces like turbomachine rotor disks during machining, as they are based on constant rotation speed, leading to empirical determination of cutting speed modulation parameters, resulting in significant time loss and discarded workpieces.

Innovation Solution

A method involving successive simulations to optimize the modulation function parameters for cutting speed variation, using a combination of geometrical, cutting force, and dynamic models to iteratively modify parameters until an acceptable surface state is achieved, allowing for controlled machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If constant rotation speed is used in machining, then the machining process is simple to control, but vibrations occur due to resonance with the workpiece natural frequencies

Engineering Contradiction:

Improvecontrol simplicityVSAvoidvibrations

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic modulation of the cutting speed around a mean value with a specific frequency that avoids the natural frequencies of the workpiece. This periodic variation in cutting speed prevents the system from entering into resonance, thereby eliminating vibrations while maintaining relatively simple control through a single modulation frequency parameter.

Inventive Principle:

Principle #19Periodic action

2Device complexity

If empirical determination of cutting speed modulation parameters is used, then no complex simulation is needed, but significant time is lost and expensive workpieces are discarded

Engineering Contradiction:

Improvesimulation complexityVSAvoidtime loss

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent performs preliminary simulation of the machining process to determine the optimal modulation frequency before actual machining begins. This preliminary action identifies the natural frequencies of the workpiece and selects a modulation frequency that avoids resonance, preventing time loss and material waste during actual machining operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses simulation results as feedback to optimize the modulation parameters. The simulation provides information about the workpiece natural frequencies and the effect of different modulation frequencies, allowing selection of optimal parameters that prevent vibrations without requiring extensive empirical testing.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If modulation function parameters are optimized through successive simulations, then vibration prevention is achieved, but computational time and complexity increase

Engineering Contradiction:

Improvevibration preventionVSAvoidcomputational time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent extracts only the essential parameters needed for vibration prevention (modulation frequency and amplitude) from the complex machining process. By focusing simulation efforts on determining these specific parameters rather than optimizing all machining parameters, the computational time is reduced while still achieving effective vibration prevention.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8655479B2Method of determining the conditions of a phase for machining a workpiece with modulated cutting rate

Publication Date: 2014.02.18 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A method of determining conditions for machining a part so as to avoid vibration appearing during the machining. A machining stage is simulated by provisionally setting parameters of a function for modulating cutting speed, by deducing a corresponding surface state, by modifying parameters iteratively with the machining stage being simulated each time until the surface state reaches an acceptable value, and by performing the machining stage by causing the cutting speed to vary in application of the corresponding modulation function.